Spindle bearings



4 Sheets-Sheet 1 Filed Feb. 5, 1964 INVENTOR WILLI H. LUEOERS N m W N i w fl I M flwws O gs Q LWLW f E:

ATTORN EY SPIN EEEEEEEEE GS NNNNNN OR W. H. LUEDERS SPINDLE BEARINGS Filed Feb. 5, 1964 4 Sheets-Sheet 4 i U J M r| 92 /0 3/ 100 L I I INVENTO-R WILLI H. LUEDERS TTORNEY United States Patent 3,385,009 SPINDLE BEARINGS Willi Henry Lueders, Waynesboro, Pa., assignor to Landis Tool Company, Waynesboro, Pa. Filed Feb. 3, 1964, Ser. No. 342,164 13 Claims. (Cl. 51-168) This invention relates to spindle bearings for machine tools, particularly grinding machines.

In a grinding operation, where a workpiece has a rough unmachined surface, the thickness or diameter of the workpiece may vary substantially so that irregular or out of round portions cause excessive wear of the grinding wheel and momentarily excessive loads on the spindle bearing.

In a centerless grinder, the control wheel and grinding wheel both are affected in this manner. In order to counteract these conditions, means is provided to permit the grinding wheel or control wheel to yield momentarily excessive loads until the high spot or out of 'round has been removed and then to hold the wheel rigidly on a fixed axis until the workpiece is ground to size.

It is, therefore, an object of the present invention to provide a spindle bearing in which a spindle can yield to abnormal grinding loads.

Another object is to provide a bearing in which the spindle can yield in one direction, but not in the opposite direction.

Anotherobject is to provide a bearing, one portion of which'has hydrodynamic bearing elements, the other portion of which has at least one hydrostatic element.

Another object is to provide means for applying one pressure to said hydrostatic element during a rough grinding operation and another pressure during a dressing operation.

7 Another object is to provide means for applying a variable pressure on said hydrostatic element, depending on the force applied from the workpiece, to urge said spindle and Wheel in the direction of a workpiece.

Another object is to provide means for applying a variable pressure on said hydrostatic element to urge said spindle and wheel in a direction opposite to that in which the spindle would normally be held by feeding pressure during a grinding operation.

Another object is to provide a bearing in which the spindle is yieldingly held against the side of the bearing adjacent the workpiece.

Another object is to provide a bearing, one portion of which has one or more hydrodynamic bearing elements above and below the horizontal centerline of the bearing, or on either side of a line designating the resultant of the external forces acting on the spindle.

The word hydrostatic as used in the specification relates to bearings in which fluid under pressure is supplied from a source outside the bearing and applied in such a manner as to support the movable member whether said member is at rest or in motion.

The word hydrodynamic as used in the specification relates to bearings in which the pressure for supporting the movable member is generated in a lubricant fluid by the movement of said member relative to a bearing member. There is no supporting pressure in the lubricant when said movable member is at rest.

FIG. 1 is a front elevation, partly in section, showing details of a bearing used to support a grinding wheel spindle with a lubricating system for supplying lubricant of different pressures to different parts of said bearing.

FIG. 2 is a sectional end elevation.

FIG. 3 is an end elevation.

FIG. 4 is a section showing the spindle in advanced position.

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FIG. 5 is a section showing the spindle in deflected position.

FIG. 6 is a hydraulic circuit.

The journal mounting consists of a housing 10. Bearing member 15, having a hydrodynamic portion 16 and having a hydrostatic portion 17, is suitably mounted in housing 10. Spindle 20 is rotatably mounted in bearing member 15.

A cutting tool in the form of a grinding wheel 21 is mounted on one end of spindle 20. Bore 25 of bearing member 15 is slightly larger than the diameter of spindle 20 so that said spindle is free to yield radially as the cutting tool engages out of round portions of a workpiece while maintaining cutting pressure between the cutting tool and workpiece.

The inner surface of portion 16 of bearing member 15 consists of peripherally spaced grooves defining two or more peripherally spaced bearing elements 35, in the upper end of portion 16, and 36 in the lower end of portion 16. Bearing elements 35 and 36 are separated from portion 17 by an upper axial groove 37 and a lower axial groove 38. Axial groove 45 separates the bearing elements 35 and 36.

Peripheral groove 30 is formed about the outer surface of bearing member 15. The inner surface 19 of portion 17 defines a pocket 18 and provides a seal to restrict the escape of lubricant, both peripherally and axially, from pocket 18 in accordance with the extent of radial displacement of spindle 20. Pocket 18, in cooperation with inner surface 19, serves to subject a constant area of spindle 20 to the pressure in pocket 18.

In portion 17, bore 25 of member 15, is connected with groove 30 by a restricted passage 50. As shown in FIGS. 1 and 3, groove 30 extends axially to provide a supply of lubricant under pressure to restrictor 60 through which a predetermined volume of lubricant is supplied to peripheral groove 61 in the inner surface of portion 16. From groove 61, said lubricant passes through grooves 37, 38, 39, 40 and 45 to provide lubrication and cooling for bearing portion 16.

Bearing member 15 is held in a predetermined position in housing 10 by means of pin 70 which extends into a notch 71 in bearing member 15. Said angular position may vary for different bearing applications depending in each case on the direction of the resultant of grinding forces acting on said bearing.

Lubricant under pressure is also supplied to radial opening in member 15. Opening 80 is connected to an axial passage 81 which, in turn, is connected to peripheral groove 82 through which lubricant under pressure is directed against a relatively narrow thrust collar 83. Opening 80 is also connected by a short restricted axial passage 85 through which lubricant under pressure is directed against thrust collar 86 having a greater exposed surface than thrust collar 83.

Axial grooves 37, 38, 39, 40 and 45 are closed in the right hand end of bearing member 15 by seal portion 90. The other end of said grooves is open and oil from restrictor 60 is distributed through peripheral groove 61 to all of said axial grooves from which it is returned through discharge passages 91 and 92 to a tank or reservoir 100. Restrictor 60 is disclosed for the purpose of illustration. Ordinarily, said grooves will receive suflicient oil for lubrication and cooling by leakage from opening 80.

Operation Lubricant under an adjustable pressure is directed through groove 30 and restricted passage 50 to bore 25 to provide a body of lubricant under pressure in pocket 18 to urge spindle 20 against bearing elements 35 and 36.

If the workpiece being ground has a uniform peripheral surface, spindle 20 will be held firmly in its normal position against bearing elements 35 and 36 and grinding wheel 21 will be supported against radial movement so that it can grind a workpiece accurately and with a superior finish.

If the peripheral surface of the rough workpiece is irregular, pressure in pocket 18 will be such as to permit spindle 20 and grinding wheel 21 to yield laterally and thus preserve grinding wheel 3.1 against excessive wear and damage until the out of round condition is gradually corrected. Then the pressure in pocket 18 will be sufiicient to hold spindle 20 and grinding wheel 21 firmly in normal position for the remainder of the grinding operation.

Restricted passage 50 is designed to effect a pressure drop so that the pressure in pocket 18 is, for example, approximately half the machine pressure. This pressure is maintained in pocket 18 by the restriction provided by the clearance between spindle 20 and inner surface 19 of bearing member 15. Any displacement of the spindle 20 from its normal or forward position will result in reducing this clearance and causing a corresponding increase in pressure in pocket 18. This increase in pressure serves to provide a more or less uniform resistance to the displacement of the spindle which is always slightly less than the force causing the displacement.

The amount of deflection is in proportion to the rise in pressure in pocket 18 due to the reduced space between spindle 20 and inner surface 19. The extent of deflection of spindle 20 may be regulated or controlled either by the size of restricted passage 50 or by changing the machine pressure in groove 30. The pressure in pocket 18 varies directly with the displacement of spindle 20 and inversely with the space between spindle 20 and inner surface 19.

In most cases, this pressure will also be sufficient to a support the wheel in normal position for dressing. Where additional pressure is needed in the hydrostatic bearing for dressing or for any other reason, it can be Sup lied by control means actuated by starting the dressing operation to connect groove 30 and pocket 18 with a higher pressure.

I claim:

1. Bearing means for supporting a journal member which consists of (a) a portion of the bearing having a bearing surface of peripherally spaced grooves defining peripherally spaced bearing elements,

(b) another portion substantially opposed to said first portion and shaped to provide a hydrostatic bearing element,

(c) means for circulating lubricant through said grooves,

(d) and means to supply a body of said lubricant under pressure to said hydrostatic bearing element to urge said journal member against said peripherally spaced bearing elements.

2. A mounting for a grinding wheel spindle comprising (a) a bearing member for rotatably supporting a spindle,

(b) said bearing member having a portion in which peripherally spaced grooves define peripherally spaced bearing elements on the side of the bearing adjacent the point of contact between a grinding wheel and a workpiece,

(c) the other side of said bearing member having a hydrostatic pressure pad for urging said spindle against said bearing elements and for providing a predetermined yielding action to a momentary increase in load on said grinding wheel during a grinding operation.

3. Bearing means for supporting a journal member which consists of (a) a portion of the bearing having a bearing surface of peripherally spaced grooves defining peripherally spaced bearing elements,

(b) another portion substantially opposed to said first portion and shaped to provide a hydrostatic bearing element,

(c) means for circulating lubricant through said grooves,

(d) means to supply a body of said lubricant under pressure to said hydrostatic bearing element to urge said journal member against said peripherally spaced bearing elements,

(e) and means to vary the pressure in said hydrostatic bearing element.

4. Bearing means for supporting a journal member which consists of (a) a portion of the bearing having a bearing surface of peripherally spaced grooves defining peripherally spaced bearing elements,

(b) another portion substantially opposed to said first portion and constructed to retain a body of lubricant under pressure to provide a hydrostatic bearing element,

(c) means for circulating lubricant through said grooves,

(d) and means to supply said lubricant under pressure to said hydrostatic bearing element to urge said journal member against said peripherally spaced bearing elements.

5. In a bearing for supporting a grinding wheel spindle,

(a) peripherally spaced bearing elements in the portion of said bearing adjacent a workpiece for determining the normal radial position of said spindle,

(b) means for permitting said spindle to yield radially in said bearing in response to external forces caused by irregularities in the surface of a workpiece engaging the grinding wheel comprising (c) a second portion of said bearing positioned substantially opposite to said first portion and having a hydrostatic bearing element,

(d) means to supply lubricant under pressure to said hydrostatic bearing element to hold said spindle against said spaced bearing elements,

(e) said hydrostatic pressure being less than that exerted on the spindle by said irregularities in the work surface, but greater than the pressure required to maintain grinding contact between said grinding wheel and a workpiece.

6. Bearing means for supporting a journal member in a machine tool which consists of (a) a portion of the bearing member having hydrodynamic bearing elements,

(b) another portion of said bearing memberpositioned substantially opposite to said first mentioned portion consisting of a hydrostatic bearing element,

(0) means for circulating lubricant through said hydrodynamic portion of said bearing member,

((1) and means to provide a body of said lubricant under pressure in said hydrostatic portion of the bearing member to urge said journal member against said hydrodynamic bearing elements.

7. Bearing means for supporting a journal member which consists of a portion of the bearing member having hydrodynamic bearing elements,

(a) another portion of said bearing member positioned substantially opposite to said first mentioned portion consisting of a hydrostatic bearing element,

(b) means for circulating lubricant through said hydrodynamic portion of said bearing member,

(c) a body of said lubricant under pressure in said hydrostatic portion of the bearing member to urge said journal member against said hydrodynamic bearing elements,

(d) the pressure of said lubricant being equal at least to the pressure required to maintain grinding contact between a grinding wheel and a workpiece.

8. Bearing means for supporting a journal member which consists of a portion of the bearing member having hydrodynamic bearing elements,

(a) another portion of said bearing member positioned substantially opposite to said first mentioned portion consisting of a hydrostatic bearing element,

(b) means for circulating lubricant through said bydrodynamic portion of said bearing member,

(c) a body of said lubricant under pressure in said hydrostatic portion of the bearing member to urge said journal member against said hydrodynamic bearing elements,

(d) said pressure being less than that exerted in the opposite direction on said journal member by out of round portions of a workpiece.

9. In combination, a bearing, a grinding wheel spindle rotatably supported in said bearing,

(a) a grinding wheel on said spindle,

(b) peripherally spaced grooves defining peripherally spaced hydrodynamic bearing elements in the portion of said bearing adjacent a workpiece for determining the normal radial position of said spindle,

(c) means for permitting said spindle to yield radially when out of round portions of a workpiece engage said grinding wheel comprising (d) a second portion of said bearing substantially opposite to said first portion and having at least one hydrostatic bearing element,

(e) means for circulating lubricant through said grooves,

(f) means to supply lubricant under pressure to said hydrostatic bearing element to urge said spindle against said peripherally spaced hydrodynamic hearing elements,

(g) said hydrostatic pressure being less than that exerted on the spindle by said out of round portions of said workpiece.

10. In combination, a bearing, a grinding wheel spindle rotatably mounted in said bearing,

(a) a grinding wheel on said spindle,

(b) peripherally spaced bearing elements in the portion of said bearing adjacent a workpiece for determining the normal radial position of said spindle,

(c) means for permitting said spindle to yield radially in said bearing in response to external forces caused by irregularities in the surface of a workpiece engaging said grinding wheel comprising (d) a second portion of said bearing member positioned substantially opposite to said first portion and having a hydrostatic bearing element,

(e) means to supply lubricant under pressure to said hydrostatic bearing element to hold said spindle against said spaced bearing elements,

(f) said hydrostatic pressure being less than that exerted on the spindle by said irregularities in the work surface, but greater than the pressure required to maintain grinding contact between said. grinding wheel and a workpiece.

11. Bearing means for supporting a journal member which consists of (a) a portion of the bearing member having a bearing surface of peripherally spaced grooves defining peripherally spaced bearing elements,

(b) another portion substantially opposed to said first portion and shaped to provide a hydrostatic bearing element,

(c) means for circulating lubricant through said grooves,

((1) means to supply a body of said lubricant under pressure to said hydrostatic bearing element to urge said journal member against said peripherally spaced bearing elements,

(c) said hydrostatic bearing element comprising a pocket in said bearing,

(f) the portion of said bearing surrounding said pocket co-acting with said journal member to restrict the flow of lubricant under pressure from said pocket, whereby the peripheral extent of said journal mem- 63 oer which is exposed to the lubricant under pressure in said pocket is substantially constant for all positions of displacement of said journal member.

12. Bearing means for supporting a journal member which consists of (a) a portion of the bearing having a bearing surface of peripherally spaced grooves defining peripherally spaced bearing elements,

(b) another portion substantially opposed to said first portion and shaped to provide a hydrostatic bearing element,

(c) means for circulating lubricant through said grooves,

((1) means to supply a body of said lubricant under pressure to said hydrostatic bearing element to urge said journal member against said peripherally spaced bearing elements,

(e) said hydrostatic bearing element comprising a pocket in said bearing,

(f) the portion of said bearing surrounding said pocket co-acting with said journal member to provide a seal to restrict the flow of lubricant under pressure from said pocket,

(g) the restricting action of said seal increasing and decreasing in accordance with the radial displacement of said spindle.

1.3. Bearing means for supporting a journal member which consists of (a) a portion of the bearing having a bearing surface of peripherally spaced grooves defining peripherally spaced bearing elements,

(b) another portion substantially opposed to said first portion and shaped to provide a hydrostatic bearing element,

(c) means for circulating lubricant through said grooves,

(d) means to supply a body of said lubricant under pressure to said hydrostatic bearing element to urge said journal member against said peripherally spaced bearing elements,

(c) said hydrostatic bearing element comprising a pocket in said bearing,

(f) the portion of said bearing surrounding said pocket co-acting with said journal member to provide a seal to restrict the fiow of lubricant under pressure from said pocket,

(g) a supply of lubricant under pressure on the outside of said bearing,

(h) a restricted passage in said bearing connecting said pocket with said supply of lubricant under pressure, whereby to provide a predetermined pressure drop between said supply of lubricant under pressure and the body of lubricant under pressure in said pocket.

References Cited UNITED STATES PATENTS lionths, vol. 106, No. 26, p. 51, Dec. 24, 1962.

LESTER M. SWINGLE, Primary Examiner.

J. A. MATHEWS, Assistant Examiner.

ROBERT C. RIORDON, Examiner. 

9. IN COMBINATION, A BEARING, A GRINDING WHEEL SPINDLE ROTATABLY SUPPORTED IN SAID BEARING, (A) A GRINDING WHEEL ON SAID SPINDLE, (B) PERIPHERALLY SPACED GROOVES DEFINING PERIPHERALLY SPACED HYDRODYNAMIC BEARING ELEMENTS IN THE PORTION OF SAID BEARING ADJACENT A WORKPIECE FOR DETERMINING THE NORMAL RADIAL POSITION OF SAID SPINDLE, (C) MEANS FOR PERMITTING SAID SPINDLE TO YIELD RADIALLY WHEN OUT OF ROUND PORTIONS OF A WORKPIECE ENGAGE SAID GRINDING WHEEL COMPRISING (D) A SECOND PORTION OF SAID BEARING SUBSTANTIALLY OPPOSITE TO SAID FIRST PORTION AND HAVING AT LEAST ONE HYDROSTATIC BEARING ELEMENT, (E) MEANS FOR CIRCULATING LUBRICANT THROUGH SAID GROOVES, (F) MEANS TO SUPPLY LUBRICANT UNDER PRESSURE TO SAID HYDROSTATIC BEARING ELEMENT TO URGE SAID SPINDLE AGAINST SAID PERIPHERALLY SPACED HYDRODYNAMIC BEARING ELEMENTS, (G) SAID HYDROSTATIC PRESSURE BEING LESS THAN THAT EXERTED ON THE SPINDLE BY SAID OUT OF ROUND PORTIONS OF SAID WORKPIECE. 